Astronomers measure primordial helium with unprecedented precision

A team of astronomers, led by Evan D. Skillman of the University of Minnesota, has measured the amount of helium produced during the first five minutes of the Universe's existence with a precision of 0.5%. This measurement is approximately three times more accurate than previous estimates, which had a margin of error around 2%.

To achieve this level of accuracy, researchers observed 15 small, distant, and chemically pristine galaxies using the Large Binocular Telescope. By analyzing over ten helium lines and 15 hydrogen lines in the spectra, the team was able to test the conditions of the early Universe, which was extremely hot and dense following the Big Bang approximately 13.8 billion years ago.

The findings, published in The Astrophysical Journal, support the Standard Model of particle physics by confirming the existence of three types of neutrinos. Skillman described the achievement as a “large-scale physics experiment” and one of the most significant discoveries of his forty-year career.